9b^2-18b-27=0

Solution for 9b^2-18b-27=0 equation:

9b^2-18b-27=0

a = 9; b = -18; c = -27;
Δ = b2-4ac
Δ = -182-4·9·(-27)
Δ = 1296
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1296}=36$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-18)-36}{2*9}=\frac{-18}{18}
=-1
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-18)+36}{2*9}=\frac{54}{18}
=3
$